Multi-pass cooker

ABSTRACT

A rotary multi-pass horizontal cooker of the type having inner and outer shell spirals with a reel between the spirals admits containers near one end of the outer shell, passes them a short distance along the outer shell spiral, transfers them to the inner shell spiral for one major inner pass, transfers them back to the outer shell spiral for a major outer pass, and discharges them directly from the outer shell.

United States Patent [191 Engdahl et al.

[ Apr. 23, 1974 MULTI-PASS COOKER [75] Inventors: Rodney A. Engdahl, Campbell;

Harry E. Barney, Jr., San Jose, both of Calif.

[73] Assignee: FMC Corporation, San Jose, Calif.

[22] Filed: Sept. 25, 1972 [21] Appl. No.: 292,015

[52] US. Cl 198/211, 198/136, 198/215, 99/365 [51] Int. Cl. B65g 29/00 [58] Field of Search 198/210-213, 198/136-154, 215; 99/354-359, 360-368 [56] References Cited UNITED STATES PATENTS 9/l9l5 I l,l54,6ll Burpee l98/2ll 2/1957 Novotny 99/365 2/1970 Mencacci 99/366 Primary Examiner-Richard E. Aegerter Assistant ExaminerRichard K. Thomson Attorney, Agent, or FirmC. E. Tripp [5 7] ABSTRACT A rotary multi-pass horizontal cooker of the type having inner and outer shell spirals with a reel between the spirals admits containers near one end of the outer shell, passes them a short distance along the outer shell spiral, transfers them to the inner shell spiral for one major inner pass, transfers them back to the outer shell spiral for a major outer pass, and discharges them directly from the outer shell.

8 Claims, 12 Drawing Figures REVERSAL END PATENTED SHEET 1 [1F 4 OUTER L PASS TRIBYJSFER START TRANSFER PA$$,8O FEED TRANSFER IN PATENTED APR 2 3 I974 SHEET 2 OF 4 JATENTEBAPR 23 19m 3 Q 805549 SHEEI 3 U? 4 FEED \o 46 REVERSAL END MULTI-PASS COOKER FIELD OF THE INVENTION This invention relates to cookers and sterilizers and more particularly a rotary type cooker wherein the articles make at least two passes through the cooker before discharge.

REFERENCE TO RELATED APPLICATIONS The copending application of Harry Barney and Rodney Engdahl, Ser. No. 292,001 filed Sept. 25, 1972 and assigned to the FMC Corporation relates to a two lane, single pass cooker that uses the interrupted reel principle for transferring one line of containers into and out of the inner shell spiral.

DESCRIPTION OF PRIOR ART The U.S. Pat. to Burpee No. 1,154,611, Sept. 28, 1915, shows a multi-pass rotary cooker of the spiral and reel type wherein the containers are introduced at one end of the outer shell spiral and traverse that shell to its other end, pass back and forth along an intermediate shell, and are transferred to an innermost shell which necessarily projects past the other shells, to accommodate discharge from the innermost shell after traversing that shell. Thus this patent requires a substantial extension of the innermost shell past the outer shells and hence the outer shells do not efficiently utilize the available length of the cooker.

The U.S. Pat. to Novotny No. 2,782,708, Feb. 26, 195 7, shows a multi-pass rotary cooker of the type generally disclosed in the aforesaid Burpee patent and having an outer shell, two intermediate shells and an innermost shell. The articles are discharged after traversing the innermost shell by passing them through the innermost shell and out through its interior. This complicates the discharge line arrangement. Also, the innermost shell itself forms the inner wall of the sealed chamber and extends past the outer shells in both directions for supporting the cooker.

The U.S. Fat. to Duncan No. 1,085,852, Feb. 3, 1914, shows a vertical two pass cooker wherein the can bottoms rest on concentric helical ramps and are pushed by rotating fingers. The cans first pass along the full length of the outer ramp, are transferred to the upper end of the inner ramp, and are discharged at the lower end of the inner ramp past the lower end of the outer ramp. The chamber is not closed.

The U.S. Pat. to McIntosh No. 1,151,111, Aug. 24, 1915 resembles Duncan, as does Baker U.S. Pat. No. 772,078, Oct. 11, 1904.

SUMMARY OF THE INVENTION The rotary cooker of the present invention is of the horizontal multi-shell and reel type and the articles traverse the spirals of both shells before being discharged. However, in accordance with the present invention, the articles are not only fed into the outer shell, they are also discharged therefrom, and hence the feed and discharge systems are simple as in conventional single pass rotary cookers. The inner shell need not project past the outer shell for accommodating discharge as in the aforesaid Burpee patent, and the inner shell need not form part of the inner wall of the sealed chamber to accommodate discharge into its interim, as in the aforesaid Novotny patent.

The ability to both feed into and discharge from the outer shell in a horizontal multi-pass cooker, contrary to the principles of the aforesaid Burpee and Novotny patents, is made possible under the present invention by a reel construction which provides a path through the cooker unlike those of prior multi-pass cookers of this type. More specifically and in accordance with the preferred form of the present invention, containers are introduced or fed through an aperture at an intermediate zone of the wall of the outer shell and into its spiral, whereupon the containers are advanced to the delivery end of that spiral, thereby making what will be termed a transfer pass. The circumferentially disposed container confining flanges on the reel (but not the radial pusher flanges) stop short of both ends of the reel by one container length. Thus at the end of the transfer pass, the containers are transferred in from the outer spiral to the inner shell spiral, whereupon they are advanced along an inner pass to the delivery end of the inner spiral. At the end of the inner pass and because of the reel construction, the containers are then transferred out, back to the outer shell spiral and are again advanced by that spiral along an outer pass to a discharge opening formed in the outer shell, which opening is somewhat upstream (relative to the outer shell spiral) of the feed opening in the outer shell. One advantage of employing the transfer pass along the outer spiral before the containers are transferred to the inner spiral is that the distance that containers being fed into the cooker must fall before they are picked up by the reel is half the distance they would fall if they were fed directly to the inner spiral.

Thus, in accordance with the present invention, the simplicity of the external feed and discharge constructions characteristic of prior single pass rotary cookers is retained and yet the advantages of shortened overall length for a given set of processing conditions characteristic (but to a somewhat lesser degree) of prior multi-pass cookers are also provided. Stated differently, for a given set of process conditions, the cooker of the present invention need be not much more than half the length of a single pass cooker of a conventional type. Although it provides two passes, it requires no extension of the inner shell for discharge or other purposes. This saves in length and reduces the beam loading on the reel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective of a cooker embodying the present invention, showing various drives, and the feed and discharge valves.

FIGS. 2 and 2A are companion schematic diagrams drawn from slightly different perspectives to illustrate the novel path taken by containers in the cooker.

FIG. 3 is a partial section through the cooker taken at the feed valve.

FIG. 4 is a developed section of a portion of the cooker looking as indicated on 4-4 of FIG. 3.

FIG. 5 is a section through the cooker as indicated on 5-5 of FIG. 3.

FIG. 6 is a fragmentary perspective showing part of the transfer pass of the cooker.

FIG. 7 is a fragmentary section at the transfer out zone, taken as indicated on 7-7 of FIG. 5.

FIG. 8 is a broken away view of the reversal end of the cooker, looking from the rear as indicated by the arrow 8 on FIG. 1.

FIG. 9 is a fragmentary perspective of the reversal end of the cooker, again looking from the rear, as in the case of FIG. 8.

FIG. 10 is a section through the discharge valve taken as indicated at 10 on FIG. 1.

FIG. 11 is a fragmentary internal view of the discharge port, taken'as indicated at 11 11 on FIG. 10.

Major elements of the Cooker Referring principally to FIGS. 1, 3 and 5, and as previously mentioned, the cooker of the present invention is a continuous rotary cooker of the horizontal spiral and reel type.

The cooker is indicated generally at K, and includes an outer drum 10, a stationary inner shell 12, an outer shell 20, (FIGS. 3 and and a reel R between the shells and which is rotated to propel containers along both shells. An inlet or feed valve 14, (FIG. 1) is mounted on the drum 10, for receiving containers from an infeed conveyor 15. A discharge valve 16 delivers processed containers from the drum to a discharge conveyor 17. Processing fluid such as steam is admitted to the drum 10 by a pipe 18 and discharged from the drum by a pipe 18a.

At this point it is to be understood that the manner in which steam and possibly water are introduced and the temperatures thereof maintained are not critical to the present invention, because this invention relates to the mechanical portions of the cooker and to the method of passing containers therethrough to obtain the advantages previously mentioned. Thus, and in this regard, reference is made to the US. Pat. to Wilbur No. 2,536,115, Jan. 2, 1951, which discloses a fluid handling system suitable for use with the cooker of the present invention, and since the details of the processing fluid system are not critical to the present invention, they are not illustrated or described herein.

The cooker is supported by legs 19 illustrated diagrammatically therein, the details of such mechanical design features not being important.

Drum and Outer Shell The drum 10 is constructed so that it forms a pressure chamber without cooperation of the inner shell 12. The drum 10 comprises an outer cylindrical shell 20 having an internal spiral or helical flight 21 seen in FIGS. 3, 4 and 5. In the arrangement illustrated herein,

the spiral flight 21 on the outer shell 20 acts to advance containers to the left, as viewed in FIG. 5.

The outer shell 20 has a feed aperture 22 (FIG. 3) which is upstream from the delivery (left) end of the outer shell spiral 21 (FIGS. 2 and 5). Under the present invention, the outer shell 20 also has a discharge aperture 23 (FIG. 10) which is below and upstream from the feed aperture 22 (relative to the outer spiral 21) as seen in FIGS. 1 and 2A. The feed aperture 22 and the discharge aperture 23 are respectively located at the feed valve 14 and the discharge valve 16, previously described in connection with FIG. 1. FIGS. 1 and 2A also show that the discharge valve 16 is in a zone that is a short distance upstream of the feed valve 14, thereby providing'optimum utilizationof the outer processing pass in the cooker.

As previously mentioned, the drum 10 of the present invention forms a self contained pressure chamber. Thus, as seen in FIG. 5, the cylindrical outer shell 20,

bearing the spiral 21, is closed by an end plate 24 at the delivery (left) end of the spiral and the end plate is apertured at 25 to receive shaft mechanism. At the right or reversal end of the cooker, the outer shell 20 is closed by an end plate 26 which is apertured at 27 for the same purpose. Since the end plate apertures are closed by shaft mechanism this construction renders the drum 10 a pressure chamber without requiring cooperation of the inner shell and hence in this respect the device resembles conventional cookers of the single pass type, except that it is much shorter.

Inner Shell In the illustrated embodiment, the inner shell 12 is fixed and its periphery is spaced by somewhat over two container diameters from the outer shell. The inner shell includes cylindrical shell 30 having end plates 32,34 that are supported on a long shaft 36. This shaft (which does not rotate) is mounted in end posts 37,38 that rest on the floor or project upwardly from the mounting framework of the apparatus, these details not being-critical to the present invention.

The inner shell 30 has an external spiral 31 which is of opposite hand from the internal spiral 21 of the outer shell 20. Thus in the embodiment being described, and as viewed in FIG. 5, the inner shell spiral 31 moves containers to the right in response to action of the reel R, whereas and as r'nentioned,the outer shell spiral 21 moves containers to the left. It will be noted that in accordance with the present invention, no discharge connections for processed containers are required for the inner shell.

Reel

The reel R rotates between the inner and outer shell spirals and serves to propel cans along both spirals, but in opposite directions. With the spiral constructions just described, the reel is rotated counterclockwise as viewed in FIG. 3.

The reel R includes an angled end ring 40 (FIG. 5) at the feed end of the cooker which is mounted on a spider 41, keyed to a sleeve 42. This sleeve extends through the aperture 25 in the end plate 24 for the drum l0 and the sleeve 42 is freely'rotatable on the shaft 36 that extends through the cooker. Keyed to the outer end of the sleeve 42 is a large gear 43 (see also FIG. 1), which drives the reel in a manner to be described presently.

The other end of the reel is of similar construction except that in the form shown, it is not driven. This end of the reel includes an end ring 44 (FIG. 5) mounted on a large spider 45 which is freely rotatable on the other end of the long shaft 36 that extends through the cooker. Actually, two stub shafts could replace the single long shaft 36, if desired.

In order to propel cans through the spirals of the outer and inner shells and to confine the containers to one spiral or the other, the reel has a plurality of circumferentially spaced, radially disposed pushing flanges 46 and each flange 46 has a circumferentially disposed confining flange 48. When the containers C are on the outside of the confining flanges 48, they are under control of the outer shell spiral 21, as seen in the upper portion of FIG. 3. However, and as seen at the upper left of FIG. 7, when the containers C are on the inside of the confining flanges 48 they are controlled by the inner shell spiral 31. An important feature of the present invention is that the circumferential confining flanges 48 stop short of the radial flanges 46 (FIG. 5) by substantially the length of one container. In other words, a container can drop through the reel between the ends of the confining flanges 48 and either end ring 40 or 44.

Drive Mechanism The details of the drive mechanism are not critical to the present invention and the drive herein illustrated is basically like that of the aforesaid Wilbur US. Pat. No. 2,536,l 16 except that in the present embodiment the reel R is only driven from one end instead of from both ends. This is feasible under the present invention because for the same cooking capacity cycle, the reel of the present invention is about half as long as that of prior single pass devices such as that in the Wilbur patent, and hence there is less tendency to distort the reel during the driving operation. Of course, eliminating one reel drive further shortens the cooker. This does not mean, however, that both ends of the reel could not be driven in accordance with the principles of the aforesaid Wilbur patent.

Referring to FIG. 1, the reel R and the feed and discharge valves 14, 16 are driven from a motor 50 and a chain and sprocket assembly 51. This assembly drives a gear box 52 which in turn drives an output chain and sprocket assembly 53. The assembly 53 drives a combined clutch-brake 54 that can be shifted as described in the aforesaid Wilbur patent, to couple the chain or sprocket drive 53 to a main shaft 55. The main shaft 55 is mounted on bearings supported by the drum and has an outer small gear 56 meshed with a somewhat larger gear 57. The larger gear 57 is keyed to a countershaft 58 which has a smaller gear 59 and this gear meshes with the large gear 43, previously described, connected to the sleeve 42 and hence to the reel R, as shown in FIG. 5.

Valves The feed valve 14 is of a known construction which is designed to continuously admit containers to the feed aperture 22 in the outer drum 10 without losing pressure within the processing chamber.

The valve includes a housing 60 (FIG. 3) having a feed aperture 61 for cooperation with the infeed conveyor (FIG. 1) previously described. The feed valve rotor 62 has container pockets 63 and is mounted on a shaft 64 which, as seen in FIG. 1, is supported in a bearing 65 on the drum 10 and is driven by a gear 66 that is meshed with the larger gear 43 that drives the reel.

The discharge valve 16 is of the same construction as the feed valve 14. The valve has a housing 70 with a discharge aperture 71 that leads to the discharge conveyor 17 previously described. The valve has a rotor 72 (FIG. 10) with pockets 73 to receive the containers from the discharge aperture 23 in the outer shell and deliver them to the discharge aperture 71 in the valve housing. The rotor 72 is mounted on shaft 74 and as seen in FIG. 1, the shaft 71 is supported on a bearing 75 on the shell and is driven by a gear 76 that also meshes with the large reel gear 43. Valves such as the feed and discharge valves 14, 16 are well known in the art and they include other features not critical to the present invention and are hence not illustrated herein.

Flow Path of Containers Before describing in detail how the various. elements of the. cooker just described provide the flow path of the present invention, the schematic diagram of that path shown in FIGS. 2 and 2A will be described, The reel R is omitted in these diagrams for clarity.

Containers C are admitted to the feed aperture 22 in the outer shell 20. As mentioned, the reel R which advances the containers along the inner and outer spirals has been omitted completely in FIGS. 2 and 2A, but it propels the containers in the direction of the small a rrows. After the containers are admitted at 22 through the outer shell 20, they start the transfer pass, indicated generally by a band 8 0. This path is along the outer spiral 21 and moves the containers to the left or delivery end of the outer shell, as viewed in FIGS. 2 and 2A. As mentioned earlier, by employing the transfer pass, incoming containers are picked up by the reel, and hence must roll only half as far as they would roll if they were fed past the reel, directly to the inner spiral.

At the end of the transfer pass 80, containers transfer in from the outer shell spiral 21 to the inner shell spiral 31 by dropping through the reel, and begin their inner pass 82. This path is to the right as viewed in FIGS. 2 and 2A. At the end of the inner pass 82, the containers on the inner spiral 31 reach the reversal end of the cooker whereupon they transfer out (dropping out through the reel) to the outer spiral 31. The containers now make an outer pass 84 along the outer spiral 31 until they reach the discharge port 23 in the shell 20, whereupon they roll by force of gravity into the discharge valve 16 as previously described. It will be noted that the discharge port 23 is not substantially more than one turn of of the outer spiral from the feed port 22, so that substantially full utilization of the available outer processing pass is used. The discharge port 23 is below the center line of the cooker to provide gravity discharge whereas the feed port 22 is above the centerline of the cooker to provide gravity infeed. Thus, as can be seen from FIGS. 2 and 2A, both the feed and discharge ports 22,23 are in the outer shell 20, and hence the associated valves 14, 16 can be mounted externally on the shell 20 and yet the containers are advanced two passes through the processing chamber.

Details of the Operation As previously mentioned and as can be seen from FIG. 5, since the circumferential confining flanges 48 of the reel R stop short of the radial pusher flanges 46 and of the reel ends 40,44, containers can pass through the reel at both ends thereof.

FIGS. 3 and 5 show how containers are fed by the feed valve 14 through the feed aperture 22 in the outer shell 20 and are picked up by the reel confining flanges 48 to make the transfer pass 80 along the outer spiral 31. These containers are confined by the circumferential flanges 48 of the reel so that they are driven by the spiral 21, and are advanced by the radial pusher flanges 46 of the reel. The central right portion of FIG. 3 also shows where the containers can transfer in by gravity from the outer spiral 21, past the ends of reel confining flanges 48 and to the inner shell spiral 31 at the end of the transfer pass 80.

FIG. 4 is a developed view which shows how the feed valve 14 (not shown) first feeds containers within the outer spiral 21 with the containers confined and supported by the circumferential reel flanges 48. This starts the transfer path 80 previously described. FIG. 4 also shows where the containers transfer in from the outer spiral 21, past the reel flanges 48 and to the inner shell spiral 31, in order to start the inner pass 82 along the inner spiral 31.

FIG. 6 is a perspective corresponding to FIG. 4 and showsthe feed into the outer spiral 21 for starting the transfer pass 80. FIG. 6 also shows how the containers transfer in by gravity at the end of the transfer pass 80 by rolling along the pusher flanges 46 past the ends of the circumferential flanges 48, for pick up by the inner spiral 31 and for starting the inner pass 82.

FIG. 7 indicates where the containers transfer out from the inner spiral 31 by gravity, rolling along the reel pusher flanges 46 at the end of the inner pass 82, for pickup by the outer spiral 21 to start the outer pass 84. It will be noted in FIG. that the section of FIG. 7 is taken just upstream of the transfer out zone, and hence the circumferential reel flanges 48 are shown in section in FIG. 7. However, FIG. 8 shows clearly that when the containers transfer out from the inner spiral 31 for pickup by the outer spiral 21, they roll past the ends of the circumferential reel flanges 48.

FIG. 9 is a perspective which shows more clearly how the transfer out operation takes place. Here containers at the end of the inner pass 82 (at the right of the cooker as viewed in FIGS. 2A and 5) transfer out past the ends of the circumferential reel flanges 48, for pickup by the outer spiral 21. This figure also shows how, since the containers are at the end ring 44 of the reel, they can roll along the radial pusher flanges 46 while clearing the confining flanges 48 that stop short of the radial flanges by somewhat over one container length.

FIG. 10 shows how processed containers C roll along the pusher flanges 46 and out through the discharge aperture 23 in the outer shell 20, at the end of the outer pass 84, as previously described. See also FIG. 2A in this regard.

FIG. 11 is an inside view looking out corresponding to FIG. 10, showing how containers being advanced by the outer spiral 21 roll out the discharge port 23 and hence into the discharge valve assembly 16.

The above detailed description of various phases of operation during a processing cycle of a cooker of the present invention will make it clear how the advantageous two pass system illustrated diagrammatically in FIGS. 2 and 2A can be obtained while permitting both the feed and discharge valves to be connected to the outer shell, and while permitting conventional drive mechanism to be utilized for the reel as shown in FIG. 5. As also previously mentioned, this construction provides a two pass cooker wherein the drum 10, that is, its circumferential shell and its end plates 24,26 substantially form the pressure or processing chamber.

By way of example only, a cooker embodying the present invention can have an outer shell that is about 10 feet in diameter and 35 feet long, and the pitch of the spirals and rate of reel rotation will be such that the cooker will process about 720 No. l0 cans per hour.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

We claim:

1. A horizontal axis rotary multi-pass cooker of the type comprising an outer shell having an internal spiral for moving containers in one direction, an inner shell having an external spiral for moving containers in the other direction, a rotatable reel between said shells, said reel having radial container pushing flanges for both spirals and circumferential container confining flanges intermediate said shells, means for feeding containers into the outer shell, means for causing the containers to traverse both spirals, and means for subsequently discharging containers from said cooker; the improvement wherein the circumferential container confining flanges of said reel stop short of the container pushing flanges by substantially one container length at both ends of the reel, said container feeding means comprising an aperture formed in the outer shell, means for causing infed containers to transfer past the associated ends of the circumferential container confining reel flanges and drop into the external spiral on the inner shell, said containers thereupon moving along an inner pass in said other direction to the other end of said inner shell and past the other ends ofjhe circumferential container confining reel flanges, whereupon the containers drop out into the internal spiral on the outer shell and are thereupon moved along an outer pass in said one direction, said container discharge means comprising another aperture that is formed in the outer shell and is disposed upstream of said feed means aperture in said one direction by not substantially more than one container length.

2. A horizontal axis rotary multi-pass cooker of the type comprising an outer shell having an internal spiral for moving containers in one direction, an inner shell having an external spiral for moving containers in the other direction, a rotatable reel between said shells, said reel having radial container pushing flanges for both spirals and circumferential container confining flanges intermediate said shells, means for feeding containers into the outer shell, means for causing the containers to traverse both spirals, and means for subsequently discharging containers from said cooker; the improvement wherein the circumferential container confining flanges of said reel stop short of the container pushing flanges by substantially one container length at both ends of the reel, said container feeding means comprising a feed aperture formed in the outer shell that is disposed at least one container length upstream of the delivery end of said outer shell internal spiral and at least several container lengths downstream of the other end of that spiral for causing infed containers to be first moved in said one direction by said outer spiral over a transfer pass and past the associated ends of the circumferential container confining reel flanges,

ternal spiral on the outer shell and are thereupon moved along an outer pass back in said one direction, said container discharge means comprising a discharge aperture that is formed in the outer shell and is disposed upstream of said feed aperture in said one direcprojecting through said end plates for supplying said' inner shell, and means for rotatably mounting said reel on said shafts between said end plates and the ends of said inner shell.

6. The cooker of claim 5, wherein said means for rotatably mounting said reel comprises a sleeve rotatable on one of said shafts and within the associated end plate, means connecting the reel to said sleeve, and means for driving said sleeve.

7. The method of handling containers in a multipass rotary cooker of the type having a horizontal axis outer shell with an internal spiral of one hand, an inner shell with an external spiral of the opposite hand, and a rotating container advancing reel between the shells;

comprising the steps of feedin g containers through the outer shell and thereafter transferring them to the inner shell spiral by gravity, advancing the containers along an inner pass to the delivery end of the inner shell spiral, transferring the containers to the outer shell spiral by gravity and advancing them along an outer pass by that spiral, and discharging the containers out through the wall of the outer shell by gravity before they reach the zone wherein the containers are being fed into the outer shell.

8. The method of handling containers in a multipass rotary cooker of the type having a horizontal axis outer shell with an internal spiral of one hand, an inner shell with an external spiral of the opposite hand, and a rotating container advancing reel between the shells; comprising the steps of feeding containers through an intermediate zone of the outer shell and into its spiral, advancing the containers to the end of the outer spiral, transferring the containers to the inner shell spiral by gravity and advancing them along an inner pass to the delivery end of that spiral, transferring the containers back to the outer shell spiral by gravity and advancing them along an outer pass by that spiral, and discharging the containers out through the wall of the outer shell by gravity before they reach the zone wherein the containers are being fed into the outer shell. 

1. A horizontal axis rotary multi-pass cooker of the type comprising an outer shell having an internal spiral for moving containers in one direction, an inner shell having an external spiral for moving containers in the other direction, a rotatable reel between said shells, said reel having radial container pushing flanges for both spirals and circumferential container confining flanges intermediate said shells, means for feeding containers into the outer shell, means for causing the containers to traverse both spirals, and means for subsequently discharging containers from said cooker; the improvement wherein the circumferential container confining flanges of said reel stop short of the container pushing flanges by substantially one container length at both ends of the reel, said container feeding means comprising an aperture formed in the outer shell, means for causing infed containers to transfer past the associated ends of the container confining reel flanges and drop into the external spiral on the inner shell, said containers thereupon moving along an inner pass in said other direction to the other end of said inner shell and past the other ends of the container confining reel flanges, whereupon the containers drop out into the internal spiral on the outer shell and are thereupon moved along an outer pass in said one direction, said container discharge means comprising another aperture that is formed in the outer shell and is disposed upstream of said feed means aperture in said one direction by not substantially more than one container length.
 2. A horizontal axis rotary multi-pass cooker of the type comprising an outer shell having an internal spiral for moving containers in one direction, an inner shell having an external spiral for moving containers in the other direction, a rotatable reel between said shells, said reel having radial container pushing flanges for both spirals and circumferential container confining flanges intermediate said shells, means for feeding containers into the outer shell, means for causing the containers to traverse both spirals, and means for subsequently discharging containers from said cooker; the improvement wherein the circumferential container confining flanges of said reel stop short of the container pushing flanges by substantially one container length at both ends of the reel, said container feeding means comprising a feed aperture formed in the outer shell that is disposed at least one container length upstream of the delivery end of said outer shell internal spiral and at least several container lengths downstream of the other end of that spiral for causing infed containers to be first moved in said one direction by said outer spiral over a transfer pass and past the associated ends of the container confining reel flanges, whereupon the containers drop into the external spiral on the inner shell and are thereupon moved along an inner pass in the other direction to the other end of said inner shell and past the other ends of the container confining reel flanges, whereupon the containers drop out into the internal spiral on the outer shell and are thereupon moved along an outer pass back in said one direction, said container discharge means comprising a discharge aperture that is formed in the outer shell and is disposed upstream of said feed aperture in said one direction by not substantially more than one container length.
 3. The cooker of claim 2, wherein said container feed aperture in the outer shell is disposed substantially one container Length upstream of the delivery end of said outer shell spiral.
 4. The cooker of claim 2, wherein said container discharge aperture in the outer shell is disposed substantially one container length upstream of said feed aperture.
 5. The cooker of claim 2, comprising end plates for closing both ends of said outer shell to form a drum, said inner shell stopping short of both end plates, shafts projecting through said end plates for supplying said inner shell, and means for rotatably mounting said reel on said shafts between said end plates and the ends of said inner shell.
 6. The cooker of claim 5, wherein said means for rotatably mounting said reel comprises a sleeve rotatable on one of said shafts and within the associated end plate, means connecting the reel to said sleeve, and means for driving said sleeve.
 7. The method of handling containers in a multipass rotary cooker of the type having a horizontal axis outer shell with an internal spiral of one hand, an inner shell with an external spiral of the opposite hand, and a rotating container advancing reel between the shells; comprising the steps of feeding containers through the outer shell and thereafter transferring them to the inner shell spiral by gravity, advancing the containers along an inner pass to the delivery end of the inner shell spiral, transferring the containers to the outer shell spiral by gravity and advancing them along an outer pass by that spiral, and discharging the containers out through the wall of the outer shell by gravity before they reach the zone wherein the containers are being fed into the outer shell.
 8. The method of handling containers in a multipass rotary cooker of the type having a horizontal axis outer shell with an internal spiral of one hand, an inner shell with an external spiral of the opposite hand, and a rotating container advancing reel between the shells; comprising the steps of feeding containers through an intermediate zone of the outer shell and into its spiral, advancing the containers to the end of the outer spiral, transferring the containers to the inner shell spiral by gravity and advancing them along an inner pass to the delivery end of that spiral, transferring the containers back to the outer shell spiral by gravity and advancing them along an outer pass by that spiral, and discharging the containers out through the wall of the outer shell by gravity before they reach the zone wherein the containers are being fed into the outer shell. 